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From 2a3a2063076b590d9ef81a7d7cdc71520647734b Mon Sep 17 00:00:00 2001
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From: Laszlo Ersek <lersek@redhat.com>
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Date: Tue, 9 Sep 2014 16:04:57 +0200
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Subject: [PATCH 07/12] pflash_cfi01: write flash contents to bdrv on incoming migration
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Message-id: <1410278697-29800-2-git-send-email-lersek@redhat.com>
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Patchwork-id: 60923
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O-Subject: [RHEL-7.1 qemu-kvm PATCH 1/1] pflash_cfi01: write flash contents to bdrv on incoming migration
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Bugzilla: 1139702
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RH-Acked-by: Dr. David Alan Gilbert (git) <dgilbert@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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A drive that backs a pflash device is special:
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- it is very small,
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- its entire contents are kept in a RAMBlock at all times, covering the
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guest-phys address range that provides the guest's view of the emulated
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flash chip.
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The pflash device model keeps the drive (the host-side file) and the
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guest-visible flash contents in sync. When migrating the guest, the
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guest-visible flash contents (the RAMBlock) is migrated by default, but on
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the target host, the drive (the host-side file) remains in full sync with
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the RAMBlock only if:
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- the source and target hosts share the storage underlying the pflash
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drive,
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- or the migration requests full or incremental block migration too, which
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then covers all drives.
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Due to the special nature of pflash drives, the following scenario makes
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sense as well:
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- no full nor incremental block migration, covering all drives, alongside
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the base migration (justified eg. by shared storage for "normal" (big)
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drives),
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- non-shared storage for pflash drives.
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In this case, currently only those portions of the flash drive are updated
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on the target disk that the guest reprograms while running on the target
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host.
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In order to restore accord, dump the entire flash contents to the bdrv in
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a post_load() callback.
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- The read-only check follows the other call-sites of pflash_update();
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- both "pfl->ro" and pflash_update() reflect / consider the case when
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"pfl->bs" is NULL;
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- the total size of the flash device is calculated as in
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pflash_cfi01_realize().
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When using shared storage, or requesting full or incremental block
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migration along with the normal migration, the patch should incur a
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harmless rewrite from the target side.
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It is assumed that, on the target host, RAM is loaded ahead of the call to
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pflash_post_load().
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Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Laszlo Ersek <lersek@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit 4c0cfc72b31a79f737a64ebbe0411e4b83e25771)
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---
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hw/block/pflash_cfi01.c | 14 ++++++++++++++
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1 file changed, 14 insertions(+)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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hw/block/pflash_cfi01.c | 14 ++++++++++++++
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1 files changed, 14 insertions(+), 0 deletions(-)
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diff --git a/hw/block/pflash_cfi01.c b/hw/block/pflash_cfi01.c
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index 18eb0bc..e8b47fb 100644
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--- a/hw/block/pflash_cfi01.c
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+++ b/hw/block/pflash_cfi01.c
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@@ -85,10 +85,13 @@ struct pflash_t {
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void *storage;
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};
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+static int pflash_post_load(void *opaque, int version_id);
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+
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static const VMStateDescription vmstate_pflash = {
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.name = "pflash_cfi01",
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.version_id = 1,
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.minimum_version_id = 1,
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+ .post_load = pflash_post_load,
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.fields = (VMStateField[]) {
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VMSTATE_UINT8(wcycle, pflash_t),
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VMSTATE_UINT8(cmd, pflash_t),
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@@ -768,3 +771,14 @@ MemoryRegion *pflash_cfi01_get_memory(pflash_t *fl)
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{
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return &fl->mem;
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}
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+
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+static int pflash_post_load(void *opaque, int version_id)
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+{
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+ pflash_t *pfl = opaque;
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+
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+ if (!pfl->ro) {
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+ DPRINTF("%s: updating bdrv for %s\n", __func__, pfl->name);
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+ pflash_update(pfl, 0, pfl->sector_len * pfl->nb_blocs);
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+ }
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+ return 0;
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+}
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--
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1.7.1
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